This invention relates to dipeptide sweeteners and more particularly to their salts which have improved solubility without significant loss of original sweetness.
It has recently been found that certain dipeptide compounds possess an intense sweetness. Examples of these compounds are set forth in U.S. Pat. Nos. 3,475,403 issued Oct. 28, 1969, 3,492,131 issued Jan. 27, 1970 and in the following published foreign patents; Republic of South Africa Pat. Application No. 695,083 filed July 12, 1969, Republic of South Africa Patent Application No. 695,910 filed Aug. 14, 1969, German Pat. No. 2,054,545 published May 19, 1971 and British Pat. No. 1,042,488 published Sept. 14, 1966, the British patent being the primary reference for the hydrochloride salt.
Generically, these compounds are represented by the Formula: ##STR1##
Wherein R represents the lower alkyls, lower alkylaryls and cycloalkyls; n stands for integers 0-5; R.sub.1 represents (a) phenyl group, (b) lower alkyls, (c) cycloalkyls, (d) R.sub.2 ##STR2## where R.sub.2 is hydroxy, lower alkoxy, lower alkyl, halogen, (e) S(O).sub.m (lower alkyl) where n is 1 or 2 and provided m is 0, or 2, (f) ##STR3## where R.sub.3 represents an hydroxy or alkoxy and (g) ##STR4## SINGLE OR DOUBLE UNSATURATED CYCLOALKYLS WITH UP TO EIGHT CARBONS.
Most suitable among these compounds are the lower alkyl esters of aspartyl phenylalanine (U.S. Pat. No. 3,492,131) wherein the stereochemical configuration is DL-L, L-L, DL-DL, or L-DL. Illustrative of the lower alkyl esters are methyl, ethyl, propyl, isobutyl, and the like, with the methyl ester being preferred for sweetness.
The dipeptides of Formula I have significant sweetening properties. Problems have arisen however, with the use of these compounds in dry systems in that their rate of solution into aqueous medium is markedly slower than sucrose, as exemplified by the methyl ester of L-aspartyl-L-phenylalanine.